Photoelectrochemical/fluorescent detection of NAD+ based on gold nanoparticles acted as ethanol dehydrogenase.

A dual-signal photoelectrochemical-fluorescent (PEC-FL) sensing method was developed for the detection of nicotinamide adenine dinucleotide (NAD+), utilizing gold nanoparticles (AuNPs) as nanozymes. Acting as ethanol dehydrogenase mimics, AuNPs catalyzed the reduction of NAD+ to NADH in the presence of ethanol. The generated NADH, serving as an electron donor, was oxidized at the surface of the ITO/BiVO4/AuNPs electrode, leading to changes in the PEC signal. Furthermore, NADH emitted fluorescence at 470 nm, enabling specific detection of NAD+. The method demonstrated excellent linearity for NAD+ concentrations ranging from 0.5 μM to 20 μM (PEC) and 2 μM-20 μM (FL). The detection limits of 0.16 μM (PEC) and 0.38 μM (FL) calculated by using 3σ/s (n = 3). Employing AuNPs as nanozymes not only addressed the challenges in NAD+ determination but also provided a new strategy for developing efficient detection methods applicable to other significant environmental and biological analytes.